Category: Perception

A short paper in the journal i-Perception presents a disconcerting visual illusion spotted “in the wild”: how stackable chairs, viewed from a certain angle, mess with your head. This is an unedited image, but your mind resists accepting it could be real. The illusion was first noticed in the office of lead author Nick Scott-Samuel at the University of Bristol, who notes in the paper that “it obtains in real life as well as in images, even when sober”.

The cause of the trick appears to be the two “edges” seen coming up from the near-base of the stack – marked AD and BC in the annotated version of the image below – which “suggests a change in depth along those lines which does not actually exist” and makes it seem as if the bars that run from one “edge” to another compose an outward face.

It misleads us a little like the Penrose triangle (see right), but whereas the triangle is actually impossible, the chairs only appear to be so – as demonstrated in this video where you can see the effect dip in and out. Scott-Samuel and his colleagues experimented with the chair stack and it appears that you need at least four chairs to create the effect.

You know the angles, you know the number: turn up to the meeting room early next time and use that recipe to astound even the most jaded eyes.

Some researchers hope that focusing on the cognitive, neural, genetic and social processes that contribute to symptom dimensions – like anxiety-depression or social withdrawal – may be more fruitful than trying to understand the causes of different diagnostic categories, like “schizophrenia” or “major depression”. It’s in this vein that a new paper in Biological Psychiatry has used a simple perceptual task to investigate how judgment confidence, judgment accuracy and metacognition (judgment insight) are related to various trans-diagnostic symptom dimensions in the general public.

We have a mostly impressive ability to identify people we know based on the sound of their voice, but prior research has uncovered an intriguing exception – we’re not very good at discerning identity from laughter. Now Nadine Lavan and her colleagues have published research in Evolution and Human Behavior that looks into why this might be and what it says about our evolutionary past.

Experienced sports players aren’t just highly skilled at executing their own actions, they also have what often seems like a supernatural ability to read the game, to watch other players and anticipate what’s going to happen next. A clever new study in Psychological Research offers insight into the brain basis of this aspect of sporting ability – the findings suggest that expert basketball players simulate in their minds the actions of other players in something akin to slow-motion, presumably giving them more time to interpret and read the actions.

Irrational beliefs – unfounded, unscientific and illogical assumptions about the world – are widespread among “the population of normal, mentally sane adults” note the authors of a new study in European Journal of Social Psychology. It’s been proposed that they arise from a mistaken perception of patterns in the world. But though this idea is popular among psychologists, there’s been surprisingly little direct evidence in favour of it. The new work, led by Jan-Willem van Prooijen at the Free University of Amsterdam, helps to fill the void.

Hallucinating voices isn’t always distressing. While the experience is commonly associated with schizophrenia, some people – an estimated 5 to 15 per cent of the general population – hear voices that aren’t real without finding it upsetting or debilitating (they may even welcome it) and in the absence of any of the other symptoms of psychosis, such as delusions or confusion.

Now new open-access research published in Brain has revealed a perceptual advantage for this group of people: they can detect hard-to-comprehend speech sounds more quickly and easily than people who have never hallucinated a voice.

In the early 1950s, while investigating rabbits’ sense of smell by recording the activity of their brain cells, the scientist Lord Adrian noticed something curious. As his team mixed up odours of increasing strength, to see at what point the rabbits’ neurons fired in response, they found the critical threshold appeared around the same point that they were able to smell the odour themselves: in other words, this suggested that the smell had become noticeable to animal and man at the same time.

On publication of the research, Lord Adrian mentioned his observation, but it didn’t provoke a serious response, presumably because informed scientists knew that the human sense of smell is generally pathetic. Everyone knew… but they knew wrong. In a new review in Science, John McGann, who runs the Rutgers Laboratory on the Neurobiology of Sensory Cognition, takes us through the historical misunderstandings to reach the truth about what the human nose knows.

The failure to reproduce established psychology findings on renewed testing, including some famous effects, has been well-publicised and has led to talk of a crisis in the field. However, psychology is a vast topic and there’s a possibility that the findings from some sub-disciplines may be more robust than others, in the sense of replicating reliably, even in unfavourable circumstances, such as when the participants have been tested on the same effect before.

A new paper currently available as a preprint at PsyArXiv has tested whether this might be the case for nine key findings from cognitive psychology, related to perception, memory and learning. Rolf Zwaan at Erasumus University Rotterdam and his colleagues found that all nine effects replicated reliably. “These results represent good news for the field of psychology,” they said.

Openness to Experience is one of the so-called Big Five personality traits and, among other things, it’s associated with being more creative, curious and appreciative of the arts. Like all the traits, where you score has important implications – for instance, there’s recent evidence that being more Open is associated with having more “cognitive reserve”, which gives you protection from the harmful effects of dementia.

Openness correlates with, but is distinct from, intelligence, and psychologists are trying to find out more about what the basis of Openness is at a cognitive and neural level. A new paper in Journal of Research in Personality shows that the trait runs deep, even affecting a very basic aspect of visual perception. It seems Open people literally see the world differently.